Hydraulic steering apparatus



Jam 17 1950 F. E. STEINMEYER 2,494,839

HYDRAULIC STEERING APPARATUS Filed April 5, 1946 4 Sheets-Sheet l 7'0RESERVOIR T0 RESERVOIR ARM Z2 HORIJON7AL7 PORTS 25a, 260.,24a CLOSED ARM22 Till? 25a NED CLOCkW/SE, 26a ops/v, 25

CONNECTED TO 24a} flaw Z 25 TURNED counlrskcwckwlss, 25:: ans 26aCONNECTED TO 240,.

T0 RESERVOIR INVENTOR.

8V WMQQV W ATTORNEYS Jan. 17, 1950 STEINMEYER 2,494,839

HYDRAULIQSTEERING APPARATUS Filed April 5, 1946 4 Sheets-Sheet 2.INVENTOR W6; ywmm ATTORNEYS Jan. 17, 1950 F. E. STEINMEYER 2,494,839

HYDRAULIC STEERING APPARATUS 4 Sheets-Sheet 5 Filed April 5, 1946INVENTOF2.

7 Wm m AT'i'oRwEvs Jan. 17, 1950 F. E. sTElNMEYER 2,494,339

HYDRAULIC STEERING APPARATUS Filed. April 5, 1946 4 Sheets-Sheet 4INVENTOR- ATTORNEYS Patented Jan. 17, 1950 UNITED STATES PATENT I OFFICEHYDRAULIC STEERING APPARATUS Frank E. Steinmeyer, Garden City,

to Colombian Bronze Corporation,

N. Y., assignor Freeport,

N. Y a corporation of New York Application April 5, 1946, Serial No.659,933

Claims.

My invention relates to improved hydraulic apparatus, and particularlyto hydraulic steering apparatus. Ihe invention is illustratedparticularly in connection with hydraulic steering apparatus for ships.1

In known apparatus for this type, it is usual to provide a pump of thereciprocating piston type. This pump is actuated by the rotation of thesteering shaft and it actuates a follower piston which operates therudder. In such known apparatus, it is necessary to move the followerpiston synchronously with the pump piston or pistons. Any. leakage inthe line destroys or lessens this synchronism.

According to my invention, it is not necessary to maintain suchsynchronism. While the invention is not limited to a pump of thereciprocating piston type or to any type of pump, it is illustrated inconnection with this type of pump. Instead of mounting the pumpcylinders upon a fixed support as in prior practice, I mount said pumpcylinder upon a turnable support which can be turned both clockwise andcounter-clockwise, around the axis of rotation of the rotatable steeringshaft. Th steering shaft actuates the pump piston or pump pistons by acam or eccentric or by crank and link connections, or any suitabledriving means. The fiow of liquid out of the pump is controlled by meansof controlling valvemeans which are fixed to the frame or casing of theapparatus. The position of the rotatable support controls the openingand closing of said controlling valve-means. The turnable support isbiased by spring means to a valve-closing position in which saidcontrollingvalve-means are closed, so as to prevent the flow of liquidout of th pump cylinders while said support is in said valve-closingposition. While the controlling valve-means are thus closed, the torquewhich is impressed upon the steering shaft by means of the steeringwheel, is also impressed upon said turnable support, by means of thepump pistons and pump cylinders, and the pressure of the operatingliquid. l

Hence, when the steering shaft is turned either clockwise orcounterclockwisethrough aselected small angle, for example, an angle of5 or less, the turnable support is initially turnedin unison with thesteering shaft through. said selected small angle, until the turningmovement of the turnable support opens said controlling valvemeans. Thefurther turning of the suppoi'tis then stopped by a suitable fixed stop.The pump then acts like an ordinary pump which is actuated by thecontinued rotation of the steering shaft. When the torque on thesteering shaft is discontinued and thepressur in the line drops to zero,the turnablesupport is moved back to its valve-closing position. Thesteering wheel can thus be turned several ievolutionsinase 2 lecteddirection, in order to turn the rudder in the selected direction throughthe desired angle. As soon as the turning of the steering wheel isdiscontinued, the valve-means are closed, by turning the support back toits valve-closing position, thus locking the rudder in its adjustedposition, until the steering wheel is again turned.

Other objects and advantages of my invention are disclosed in theannexed description and drawings.

Fig. 1 is a diagrammatic top plan View, partially in horizontal section.Th pump which is illustrated is a two-cylinder pump. Fig. 2 is a rearvertical elevation of a commercial embodiment, the representationof therear vertical cover of the casing having been omitted.

Fig. 3 is a top plan view of Fig. 2, partially in horizontal section,taken below the top wall of the casing.

Fig. 4 is a vertical longitudinal section through the line 4-4 of Fi 2.

The principle of the invention will be explained with reference to Fig.l.

Eccentric 2 is fixed to the horizontal, rotatable steering shaft I, sothat eccentric 2 and shaft I are turned in unison. Shaft I has a centralaxis of rotation 43. The eccentric 2 is the usual cylindrical disc, andit has a horizontal central axis 44. Fig. 1 shows the turnable support18 in the position in which the controlling valve-means are closed. InFig. 1, the axis 44 of eccentric 2 is located vertically above axis 43of steering shaft I. For convenience, the vertical line 415 and thehorizontal line 42 are designated respectively as the major axis and theminor axis of the eccentric 2. The horizontal line 42 intersects theaxis 44 of eccentric 2.

In Fig. 1, the pump cylinders 5 and 6 and the pump pistons 3 and 4 arehorizontally disposed. Said pump pistons 3 and 4 have outer and planarwalls of circular contour, which abut the periph ery of eccentric 2 attwo horizontal lines which are perpendicular to the plane of Fig. 1, andwhich are defined by the ends of line 42. The horizontal line 4|, whichintersects the axis 43 of shaft I, is coincident with the common lateralaxis of cylinders 5 and 6, and pistons 3 and 4. The pistons 3 and 4 arebiased towards eccentric 2, so that said pistons always abut thecylindrical periphery of eccentric 2 when the pumping action takesplace, by means of compression springs which are located in thecylinders 5 and 5.

The turnable support [8 is yieldingly maintained in its position of Fig.1, by suitable springmeans such as 32-32 shown in Fig. 2.

Pump cylinders 5 and 6 have flexible outlet pipes l and 8 which areconnected to manifold l6, and flexible inlet or suction pipes I l and12, which are connected to a reservoir for the oil or other operatingliquid.

Between the cylinders 5, 6 and manifold I6, the flexible outlet pipes 1and 8 are provided with outlet check-valves which are located in casings9 and Ill, so that the liquid can flow only outwardly through outletpipes I and 8. These casings 9 and I are fixed to the frame or casing ofthe apparatus.

Between the cylinders and 6 and the reservoir, the flexible inlet pipesI I and 'l2 are provided with inlet check-valves in casings H and 19, sothat liquid can flow only inwardly in said pipes I! and I2. Thesecasings I 4 and I5 are also fixed to the frame or casing of theapparatus.

These check-valves are conventional and are not shown. The manifold I6is also fixed to the drarne or casing of the apparatus.

The controlling valve' means are located in a casing *I 'I, which isfixed to the frame or casing of the apparatus. Thesecontrollingvalve-means can be, for example, an Electrol valve which is fullydescribed in U. S. Patent No. 2,349,069 granted'May 1944. For thisreason, the controlling valve-means are not illustrated.

Manifold I6 connected toaiport of easing I I by a pipe I6a, The controlvalves in casing H are of the non-leak .poppet type.

Respectiveoutlet pipes 25a'n'd 26 are'conne'cted to respective ports 25aand 26a of casing II. Another pipe 24 is connected at one end thereof to"a port 24a of casing 1 1, and at its other end to the same reservoir towhich the inlet pipes I I and 1 2 are connected.

The poppet valves in v'alve='casing H are actuated and controlled byshaft 23, to which arm 22 is fixed. I

When the turnable support I8 and arm 22 are Ehorizont'al, al1 thevalvesinc'asing I? are closed, so that no liquid can flow through pipes Mia,25, 2 1,26. The cas'ing I'I is always filled with-liquid.

When ar'm 22 is turned olocl'cwise from its hori- 'z'ontal position to alownw "aroly inclined position through an angle of less than 90, liquidis f-ree to enter valve-casing 11 "through pipe Ito, and to pass out ofvalve-"ca's'i-ng '-I'I only through :pipe 26. Insuch position of arm 22,liquid which enters valve-casing I7 through pipe 25 can flow onlythrough pipe 24 to the reservoir.

'When arm 22 is turned counterclockwise through an a'ngle of "less 'than90 to an upwardly inclined position, liquid can enter valve-casing 17through pipe IGa, "pass out through pipe 25, and the liquid which enterscasing H through pipe '2 to the reservoir.

Arm 2-2 -'is turnabl-y connected by pivo't pin 21 toalink'lal, 'whichis' turnably connected by pivot pin 28 to the 'turnalole sii port -18.

Pipes 25 and 26 are connected to respective ports -21 and aaor a-=fixeacylinder 29. The follower piston'30 is recipro'cated between ports 21and 28. This follower "piston '30 'actuates the rudder by conventional*means, which are not shown. The cylinder 29 isfmade of sufficientvolume between ports 27 and 28, so that "it requircs a plurality'of'coinplete revolutions of the steering shaft I, to move "the followerpiston 38 from one extreme position thereof to its other extremeposition.

To 'explain the "operatioh of the device, it is assumedthatthe's'teering shaf t l is turned clockwise, When the parts are inthe respective posrtions of Fig. 1.

When eccentric 2 is'turned clockwise, it urges piston 4 inwardly in its'c'ylinde'rfi, thus producing pressure upon the incompressible liquid inoutlet pipe 8, manifold I6 and pipe 16a. This liquid cannot enter casingII, because all its valves are then closed. This liquid cannot flowreversely in pipe I, because of the check-valve in casing 9. The piston'4 is thus, in effect, locked to eccentric 2. 'The eccentric 2 'thusexerts a clockwise torque upon support I 8, so that its turns clockwisein unison with eccentric 2. When support I8 is thus turned, the shaft 23is turned clockwise by arm '22 and link I 9.

There may be afslight play between the parts. As "soon a's arm 22 isthus turned clockwise through a small angle, liquid can fiow out ofcylinder 6 through pipe 8 through manifold I6, pipe 16a, casing I'I,pipe 26, but not through pipes 25 and 24. Pressure is thus exerted uponthe follower piston 30, to move it towards :port 21, thus turningthe-rudder in the selected direction. The liquid which is thus pumpedout of cylinder :6, must therefore be pumped against the load pressurewhich is required to actuate the follower piston ilfl. -The force whichis exerted by eccentric '2 against piston 4, is =-applied along a linewhich 'is above axis 43-, until eccentric 2 has been turnedsubstantially 90 "from its position of Fig. 1,

Hence the eccentric 2 will apply a clockwise torque upon-supportI8,1untileccentric2 has been turned substantially 90 from 'its positionof Fig. 1, making allowance for the small angle in which support I 8-istur'nedin unison withsnaft I.

The turning inovement of support I8 around the axis 43st shaft 1 isstopped by a suitable fixed stop, when support I8 has-"been turned fromits position of Fig. 4 through a selected 'angle. For example, thisselected nngle may be 5 01 less.

when 's'liaft "and ec n'tric 2 'arethus turned clockwise from theirpositions of Fig. 1, the eccentric 2 will f'or'ce piston l inwardly inapumping stroke in its cylinder is, until the "line 15 or eccentric 2 ison line II, while holding "sup ort I8 turned clockwise "from itsposition of Fig. 1, a ainst the aforesaid stop. While piston 4 is thusmoved in its pressure or pumping stroke, the piston 3 is mov d outwardlyby its compression'spr'in'g in its cylinder '5 in a suction stroke. IWhen eccentric '2 is turned clockwise through I "from said position inwhich line 45 is on line H, to a positionin which line 45 is again online II, the piston '3 is moved inwardly in its cylinder --5 in arespective pressure or .pumping stroke, and piston 4 is moved outwardlyby its compression spring in cylinder 6 ins respective suction.--stroke, while the clockwise torque is maintained uponsupport I8.

Further clockwise "rotation of eccentric -2 'during the next quarterrevolution, back to the position -of Fig. 1, 'causes outward movement ofpiston 3 and inward movement of pisto'n 4.

During the pressure or pumping sm-lake of piston :3, liquid is :puinpedout of cylinder 5 through its flexible outletspi e I, through manifold1e, .Ipipe- 1e21, eas ing I 1, and to pipe 26, but nottnrough pipes-'2E-a'nd1'24. The follower 'piston 30isthus 'fuitheractuated towardsport-21.

Hence the steering shaft "I can'be turnedclock"- wise throughseveralcomplete revolutions, to -recipro'ca-te the m'ppistons and "4 inalternate pressure and'suc t'lo strdkes, while supplying liquid under"pressure through pipe 26, to "actuate the follower piston 31'! "in the"same selected direction.

The same operation *is secured when the steering sha'ft I 'i's 'tu'r'nedcounterclockwise, in which case the support I8 is held tilted"counterclockwise through the selected angle, until the support l8 abutsanother stop.

When the rotation of shaft l is stopped, the pressure of the liquid inthe respective power line drops to zero.

As an example, it is assumed that the clockwise rotation of the shaft isstopped, when the major axis 45 is in the vertical position of Fig. 1.At this time, the support I8 is slightly tilted clockwise from itshorizontal position, preferably through a maximum angle of or less.Immediately prior to the time that transverse line 45 of eccentric 2again reaches its position of Fig. 1, piston 3 is moving outwardly inits cylinder 5 and is approximately midway in its suction stroke; piston4 is moving inwardly in cylinder 6 and is approximately midway in itspumping stroke; support I8 is tilted clockwise from its position of Fig.1, through the aforesaid small angle, and follower piston 30 is movingforwardly towards port 21. At this time, the piston 4 contacts theeccentric 2, along a lateral horizontal line which is in the plane ofline 42. The momentum of piston 4 and of the liquid which is thensubjected to pressure by piston 4, will move piston 4 slightly away fromeccentric 2, when line 45 resumes its position of Fig. l, and themomentum of piston 3 and the liquid in its suction line will forcepiston 3 against eccentric 2 at the level of line 42. This will relievethe counterclockwise torque on support I8, so that its spring means,such as the springs 32--32 shown in Fig. 2, will return said support Itto its normal horizontal position of Fig. 1, thus closing the valves incasing l1, and locking the rudder in its adjusted position.

When the shaft I is turned counterclockwise, each pumping stroke of eachpiston 3 and 4 will force liquid out of casing through pipe 25, but notthrough pipes 24 and 26.

When the follower piston 30 is moved towards front port 21, the liquidwhich is in front of piston 3|] is forced through pipe 25, and suchliquid is by-passed in casing I! through pipe 24 to the reservoir.Similarly, the liquid which flows through pipe 26 to casing I! whenpiston 30 is moved rearwardly, is by-passed through pipe 24 to thereservoir.

If the eccentric 2 is replaced by other driving means for the pump,there is sufiicient play in such driving means, or sufficient play inthe control valves, to turn the support It through the required smallangle to horizontal position, when the actuation of shaft is stopped. I

As shown in Fig. 3, the practical embodiment of Figs. 2-4 has twoeccentrics 2 and 2a. The eccentric 2 operates the pump pistons 3 and 4,and eccentric 2a operates pistons 3a and 4a. The operation is the sameas in the embodiment of Fig. 1. These pump pistons have bearing plates Badjacent the eccentrics 2 and 2a.

Fig. 3 shows one of the compression springs S, which urges therespective pump piston outwardly in its respective cylinder in arespective suction stroke against the periphery of the respectiveeccentric.

The parts are located in a casing 3|, which has a removable cover 3|a.This casing 3| is filled with oil or other liquid, up to the level ofthe line L in Fig. 2.

The support I8 is a frame which is turnable around bearings which arecoaxial with the axis of shaft I.

Fig. 2 shows two tension springs 32. Each tension spring 32 has a longU-shaped end 33 which i .slidably embraces a respective plate of supportl8. Thus, if the support I8 is turned clockwise from its horizontalposition of Fig. 2, the left spring 32 will be extended to exert itstension, and the support I8 will slide relative to the slideend 33 ofthe right spring 32, thus creating a counter torque which biases supportl8 back to its horizontal position.

In the commercial embodiment of Figs. 2-4, one end-portion of support I8is turnably connected by a pivot'pin 20 to a link 35, which is turnablyconnected by a pivot pin 31 to a lever 60, which is turnably connectedto fixed casing 3| by a pivot pin 34. Lever 6B is turnably connected bypivot pin 36 to the link l9, which is normally horizontal in thecommercial embodiment, in which the arm 22 is normally vertical. Thenormally horizontal link I9 is connected by a pivot pin or ball-joint 2|to the normally vertical arm 22.

The cylinders 3 and 3a have respective outlet pipes and la andrespective inlet pipes H and Ila. The check-valve for pipes I and la arelocated respectively in casings 9 and 9a. The check-valves for the inletpipes H and Ila are located respectively in casings l4 and Ma.

Fig. 4| shows only a part of pipe lfia. This pipe |6a is connected toport |6b of manifold It. The outlet check-valve casings such as 9 and9a, are connected directly to manifold It, by means of suitable alinedports.

Pipe 25 is connected to a coupling 25a which is fixed to the bottom wallof casing 3|, and pipe 26 is connected to a similar coupling 26a. Thesecouplings are also respectively connected to the respective ports 21 and28 of the cylinder 29.

Since the parts which are not shown in Figs. 2 and 4 are duplicates ofthe illustrated parts of Fig. 1, the construction is clear.

As an example, when shaft is turned clockwise as viewed in Fig. 2, thesupport |8 is turned initially clockwise in unison with shaft I, thustensing the left spring 32, while the support l3 slides relative to theU-end 33 of the right spring 32. This provides a reverse orcounterclockwise torque upon support I8. The lever 60 is thus turnedcounterclockwise by link 35, thus actuating link I!) to turn shaft 23clockwise, until the lower end-portion of lever 60 abuts the wall ofcasing 3|. Since the casing 3| is filled with oil below the line L, theblow of lever 63 against the wall of easing 3| will be cushioned, thuseliminating objectionable noise and vibration. The lever 63 thus acts asa stop for support |8, so that it remains tilted in clockwise positionat a small angle, While the clockwise rotation of shaft is continued.

When the shaft is turned counterclockwise, the right spring 32 istensed, and the support I8 slides relative to the U-end 33 of the leftspring 32. Link 35 is now raised to turn lever 63 clockwise, thusturning shaft 23 counterclockwise. The

upper end-portion of lever 60 then abuts the wall of casing 3|, thusproviding the necessary stop. In Fig. 2, the axes of the pivot pins 3'!and 34 are in the same horizontal line.

I thus use a single lever 60 for operating the shaft 23 and to functionas a stop.

As shown in Fig. 4, the top of casing 3| has a vent cap C, so that theinternal pressure of casing 3| is always equal to external atmosphericpressure.

I have described a preferred embodiment of my invention, but numerouschanges and omissions and additions can be made without departingfaaicnsee .r'e'cipro'cated between thep'orts i2?! :and 328, representany kind :of servo motor'whichis operated we rby the discharge of liquidzfrom a pressure pump -:of any type, which :is v.operatively connectedto shaft l. The invention alsoiappliesfzoapparatus in which the shaft lis rotate'd'ina single selected direction.

The apparatus can "be used for :steering -ve- FhiCIBS in additionto'steering ships.

'In the specific embodiment disclosed, the

f'pump-operating means 2 also move the support Hi from its normalposition :in'Fig. .1 to a posi- 131011 in which said support 15B alsoholds the controlling valve-means in casing 17, in respective open andclosed positions, but the invention is not limited to this dual functionof said pumpoperatin means.

While I have illustrated a pressure hydraulic pump, the invention is notlimited thereto, and it is not necessarily :limited to the use ofanydraulic system, because the operating fluid may be air or a gas,in-any type of power transmission H The cylinder '29 and piston 3 0exemplify "a reversible servo-motor which may be of any type and whichhas respective ports, as exemplified by ports 2! and 28, through'whichthe operating fluid can enter said servo-motor and pass out of v saidservo-motor. The direction of movement of said servo-motor depends uponthe direction of movement of the operating fluid in said servomotorbetween said ports. The controlling valvemeans are adapted toconnectieither of :said ports to said pump. Thesecontrolling valve-meansare connected in any manner to the shaft, so that when the shaft isturned :inone direction, one of said ports remains connected 'to saidpump, and when the shaft is turned in the reverse direction, the otherport remains connected to said .pump, While the shaft is turned throughany desired angle. Optionally, said controlling valvemeans are biased soas to close both said ports when the shaft is stationary.

The ports by which pipes 25, 24, '26 are respectively connected tocasing H, are respectively designated as 25a, 2504,2611. The leg-endadjacent Fig". 1 sufiiciently designates the operation of thecontrolling valve-means in "casing ll, since the I same are well-knownper se.

I claim: 1. Hydraulic apparatus which comprisesarotatable shaft, a pumpoperatively connected to said shaft by pump-operating'means andopera'ted -:by the'rotation of saidshaft to discharge liquid from saidpump, a servo-motor connected :to said pump by connectin-pipe-means,:said servo-motor being operated by the liquid which isdischarged from said pump through said pipe- 7 means, movablecontrolling valve-.means located in said pipe means between :saidpump'andsaid s61V0mOtOl, said controlling valve-rneans being movable toa closing position to prevent'theflow of liquid through said pipesmeansfrom said pump to said servo-motor, said controlling valve- :means beingalso movable to :an open position to permit said now of .liquid, saidpump being .ifixed to a .rnovable support, said support being connectedto said controlling valve-means byconnecting means to operate saidcontrolling valvemeans to either of said positions, said support beingbiased by biasing means to a :normal :posi- "tion in which said supportholds said controlling valve-means in :said closing position, said shaftrotatable shaft, a pump operatively connected to .said :shaft bypump-operating means and operrated :by the rotation of said shaft ineither direction to discharge liquid from :said pump, :a servo-motorwhich has two sides and Which is operable in two opposite directions,said servo- :motor being oonnectedto said pump by connect- :ing :pipemeans "which :are connected to the two opposite sides of .said servomotor, said servom'otor being operated by the liquid which is dischargedfrom said pump through said pipemeans, movable controlling valve-meanslocated finisaid pipe-means between said pump and said servo-motor, saidcontrolling valve-means be- :ingmovable :to respective closing andopening positions to respectively prevent and permit the flowof liquidfrom said pump to said servo-motor and to direct the flow of said liquidinto either of 'the two sides of said servo-motor, thereby controllingthe direction of operation thereof, said pump being fixed to a supportwhich is turnable :around the axis of said shaft, stop-means for 3niiting the turning movement of said support in respective opposeddirections, said support be- Ling connected to said controllingvalve-means by connecting means to operate said controlling valve-meansto either of said positions, said turnable support being biased bybiasing means to a normal position in which said support holds saidcontrolling valve-means in said closing position, 'said pump-operatingmeans being constructed and operative to turn said support in unisonwith said shaft until -'ie turning movement of said support is stoppedby said stopmeans, said pump-operating means being constructed andoperative to continue to operate said pump upon continued rotation ofsaid shaft after said turning movement of said support has been stopped,said support holding said controlling valve-means open in a respectiveselected opening position and directing the'flow of liquid into aselected side of the servo-mo'torto operate said servo-motor 'by saidpump in a selected direction by the continued rotation of said shaftwhen said support abuts said stop-means, the pipe-means which areconnected to a respective end-of said servo-motor temporarily acting asan inlet for said servo-motor when it .is operated in one direction andtemporarily acting as an outlet for said servo-motor when it.isoperate'd in the opposed direction, said controlling valvemeans beingconnected through an openport to an exhaust for said servo-motor andconnecting to said exhaust the pip -means which are tempiston-axis whichintersects and is lateral to the shaft-axis, said shaft and saideccentric bein located between said pistons, each said cylinder havingan inlet pipe which is connected through an inlet check-valve to areservoir, each said cylinder having an outlet pipe which is connectedthrough an outlet check-valve to a casing in which controllingvalve-means are located, said controlling valve-means being operated bya valve-shaft, said valve-shaft being connected to said turnablesupport, a servo-motor which comprises a servo-cylinder which haslongitudinally spaced ports and a servo-piston which is slidable in saidservo-cylinder between said ports, a first servo-pipe which connectssaid casin to one of said ports, a second servo-pipe which connects saidcasing to the other of said ports, a third pipe connected at one end tosaid casing and connected at its other end to said reservoir, saidcontrolling valve means being movable (a) to a. position in which saidcasing is closed; (1)) to respective positions in each of which liquidcan enter said casing through a selected outlet-pipe and liquid can flowout of said casing through a selected servo-pipe and liquid can entersaid casing through the other servo-pipe to be lay-passed to saidreservoir through said third pipe; said support being biased by biasingmeans to a normal position in which it holds said controllingvalve-means in said position (a); said support holding said controllingvalve-means in said position (b) when said support abuts said stopmeans.

4. Hydraulic steering apparatus comprising a steering shaft, aneccentric mounted on said shaft, a pair of cylinders on diametricallyopposite sides of said eccentric, fluid in said cylinders, a pair ofpistons in said cylinders in operative engagement with said eccentricwhereby rotation of the steering shaft and of the eccentric mountedthereon causes reciprocating movement of the pistons, said pistoncylinders being mounted on a pivotable support whose pivot coincideswith the longitudinal axis of the steering shaft, stop members whichlimit the pivotal movement or said pivotally mounted support, tensionmeans connected to said pivotally mounted support and normally urgingsaid support into a neutral position, the torque action of said steeringshaft upon said pivotal support through the pistons which the eccentricon said shaft engages being such as to cause pivotal movement of thepivotal support against the action of the tension means and in thedirection in which the steering shaft is turned, such pivotal movementceasing when the pivotal support engages a stop member, further turningmovement of the steering shaft causing axial movement of the pistonswithout affecting the angular position of the pivotal support, a valve,fluid in said valve, pipelines connecting the two cylinders with saidvalve, a fluid operated servo-motor which has two sides and which isoperable in opposite directions, pipelines connecting said valve to thetwo sides of said servo-motor and valve controlling means connected tosaid pivotal support whereby pivotal movement of said support operatessaid valve and opens and closes the pipelines to the respective sides ofthe servo-motor, whereby the servo-motor is caused to operate in onedirection when the flow of liquid under pressure is admitted by thevalve into one side of said servo-motor and whereby the servo-motor iscaused to operate in the opposite direction when the flow of liquid isdirected into the opposite side thereof by said valve, each pipelineoperating temporarily as an inlet for said servo-motor when it isoperated in one direction and operating temporarily as an outlet forsaid servo-motor when it is operated in the opposite direction, anexhaust for said servo-motor, said valve being actuated to connect thepipeline which is temporarily acting as an outlet to said exhaust whensaid pivot support engages a stop member.

5. Hydraulic steering apparatus comprising a steering column, arotatable support mounted on said steering column, said support beingco-axial with said steering column, tensioning means connected to saidrotatable support and tending to hold said support in neutral position,stop members adjacent said support which limit the angular movement ofsaid support, a pair of diametrically opposed cylinders mounted on saidsupport, pistons and liquid under pressure in said cylinders, and aneccentric fixedly mounted on said steering column and operativelyengaging said pistons, whereby rotary movement of said steering columnprovides a torque action upon the support through said eccentric, saidpistons and said liquid under pressure, causing pivotal movement of saidsupport in the direction of rotation of said steering column against theaction of the tension means connected thereto, said pivotal movement ofthe support ending when the support is brought into contact with one ofthe stop members, further rotary movement of the steering column causingactuation of said pistons in their respective cylinders, pipelinesconnected to said cylinders, a valve connected to said pipelines, asource of liquid under pressure connected to said valve, additionalpipelines connected to said valve and a fluid operated servo-motorconnected to said additional pipelines, said servo-motor being operablein two opposite directions and having two sides to receive said liquidunder pressure through said additional pipelines, said valve beingconnected with a controlling member which is operatively connected tothe rotatable support, whereby angular movement of said support inresponse to rotation of the steering column causes the valve to open andclose to direct the flow of liquid under pressure through the additionalpipelines into either side of the servo-motor, thereby causing saidservo-motor to operate in a selected direction, each pipeline operatingtemporarily as an inlet for said servo-motor when it is operated in onedirection and operating temporarily as an outlet for said servo-motorwhen it is operated in the opposite direction, an exhaust for saidservo-motor, said valve being actuated to connect the pipeline which istemporarily acting as an outlet to said exhaust when said pivot supportengages a stop member.

FRANK E. STEINMEYER.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 564,265 Wiking July 21, 18962,236,467 Clench Mar. 25, 1941 FOREIGN PATENTS Number Country Date360,458 Great Britain Nov. 2, 1931

